[lvm-devel] master - scanning: open devs rw when rescanning for write
David Teigland
teigland at sourceware.org
Fri Jun 21 15:58:21 UTC 2019
Gitweb: https://sourceware.org/git/?p=lvm2.git;a=commitdiff;h=d16142f90fdcf2aef42a51ecabd0c4ff11733d7c
Commit: d16142f90fdcf2aef42a51ecabd0c4ff11733d7c
Parent: 8fecd9c14e0b3f62cc4de6ddac0a015db687b335
Author: David Teigland <teigland at redhat.com>
AuthorDate: Tue Jun 11 16:17:24 2019 -0500
Committer: David Teigland <teigland at redhat.com>
CommitterDate: Fri Jun 21 10:57:49 2019 -0500
scanning: open devs rw when rescanning for write
When vg_read rescans devices with the intention of
writing the VG, the label rescan can open the devs
RW so they do not need to be closed and reopened
RW in dev_write_bytes.
---
lib/cache/lvmcache.c | 17 ++++++++-
lib/cache/lvmcache.h | 1 +
lib/label/label.c | 32 ++++++++++++++++-
lib/label/label.h | 1 +
lib/metadata/metadata-exported.h | 5 ++-
lib/metadata/metadata.c | 72 ++++++++++++++++++++++++-------------
tools/lvchange.c | 2 +-
tools/pvscan.c | 2 +-
tools/vgchange.c | 4 ++-
9 files changed, 103 insertions(+), 33 deletions(-)
diff --git a/lib/cache/lvmcache.c b/lib/cache/lvmcache.c
index 1d92e01..e2d19e8 100644
--- a/lib/cache/lvmcache.c
+++ b/lib/cache/lvmcache.c
@@ -772,7 +772,7 @@ next:
* to that VG after a scan.
*/
-int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid)
+static int _label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid, int rw)
{
struct dm_list devs;
struct device_list *devl, *devl2;
@@ -804,7 +804,10 @@ int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const
/* FIXME: should we also rescan unused_duplicate_devs for devs
being rescanned here and then repeat resolving the duplicates? */
- label_scan_devs(cmd, cmd->filter, &devs);
+ if (rw)
+ label_scan_devs_rw(cmd, cmd->filter, &devs);
+ else
+ label_scan_devs(cmd, cmd->filter, &devs);
dm_list_iterate_items_safe(devl, devl2, &devs) {
dm_list_del(&devl->list);
@@ -819,6 +822,16 @@ int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const
return 1;
}
+int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid)
+{
+ return _label_rescan_vg(cmd, vgname, vgid, 0);
+}
+
+int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid)
+{
+ return _label_rescan_vg(cmd, vgname, vgid, 1);
+}
+
/*
* Uses label_scan to populate lvmcache with 'vginfo' struct for each VG
* and associated 'info' structs for those VGs. Only VG summary information
diff --git a/lib/cache/lvmcache.h b/lib/cache/lvmcache.h
index 5b78d7a..e2d967c 100644
--- a/lib/cache/lvmcache.h
+++ b/lib/cache/lvmcache.h
@@ -71,6 +71,7 @@ void lvmcache_destroy(struct cmd_context *cmd, int retain_orphans, int reset);
int lvmcache_label_scan(struct cmd_context *cmd);
int lvmcache_label_rescan_vg(struct cmd_context *cmd, const char *vgname, const char *vgid);
+int lvmcache_label_rescan_vg_rw(struct cmd_context *cmd, const char *vgname, const char *vgid);
/* Add/delete a device */
struct lvmcache_info *lvmcache_add(struct labeller *labeller, const char *pvid,
diff --git a/lib/label/label.c b/lib/label/label.c
index a8d87ec..185e51b 100644
--- a/lib/label/label.c
+++ b/lib/label/label.c
@@ -1118,7 +1118,37 @@ int label_scan_devs(struct cmd_context *cmd, struct dev_filter *f, struct dm_lis
_scan_list(cmd, f, devs, NULL);
- /* FIXME: this function should probably fail if any devs couldn't be scanned */
+ return 1;
+}
+
+/*
+ * This function is used when the caller plans to write to the devs, so opening
+ * them RW during rescan avoids needing to close and reopen with WRITE in
+ * dev_write_bytes.
+ */
+
+int label_scan_devs_rw(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs)
+{
+ struct device_list *devl;
+
+ if (!scan_bcache) {
+ if (!_setup_bcache(0))
+ return 0;
+ }
+
+ dm_list_iterate_items(devl, devs) {
+ if (_in_bcache(devl->dev)) {
+ bcache_invalidate_fd(scan_bcache, devl->dev->bcache_fd);
+ _scan_dev_close(devl->dev);
+ }
+ /*
+ * With this flag set, _scan_dev_open() done by
+ * _scan_list() will do open RW
+ */
+ devl->dev->flags |= DEV_BCACHE_WRITE;
+ }
+
+ _scan_list(cmd, f, devs, NULL);
return 1;
}
diff --git a/lib/label/label.h b/lib/label/label.h
index 07bb77d..f06b7df 100644
--- a/lib/label/label.h
+++ b/lib/label/label.h
@@ -104,6 +104,7 @@ extern struct bcache *scan_bcache;
int label_scan(struct cmd_context *cmd);
int label_scan_devs(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs);
+int label_scan_devs_rw(struct cmd_context *cmd, struct dev_filter *f, struct dm_list *devs);
int label_scan_devs_excl(struct dm_list *devs);
void label_scan_invalidate(struct device *dev);
void label_scan_invalidate_lv(struct cmd_context *cmd, struct logical_volume *lv);
diff --git a/lib/metadata/metadata-exported.h b/lib/metadata/metadata-exported.h
index 9029d3f..966c88f 100644
--- a/lib/metadata/metadata-exported.h
+++ b/lib/metadata/metadata-exported.h
@@ -184,8 +184,9 @@
#define READ_ALLOW_EXPORTED 0x00020000U
#define READ_OK_NOTFOUND 0x00040000U
#define READ_WARN_INCONSISTENT 0x00080000U
-#define READ_FOR_UPDATE 0x00100000U /* A meta-flag, useful with toollib for_each_* functions. */
-#define PROCESS_SKIP_SCAN 0x00200000U /* skip lvmcache_label_scan in process_each_pv */
+#define READ_FOR_UPDATE 0x00100000U /* command tells vg_read it plans to write the vg */
+#define PROCESS_SKIP_SCAN 0x00200000U /* skip lvmcache_label_scan in process_each_pv */
+#define READ_FOR_ACTIVATE 0x00400000U /* command tells vg_read it plans to activate the vg */
/* vg_read returns these in error_flags */
#define FAILED_NOT_ENABLED 0x00000001U
diff --git a/lib/metadata/metadata.c b/lib/metadata/metadata.c
index 039a7d6..7b0d6ce 100644
--- a/lib/metadata/metadata.c
+++ b/lib/metadata/metadata.c
@@ -4476,7 +4476,8 @@ void vg_write_commit_bad_mdas(struct cmd_context *cmd, struct volume_group *vg)
static struct volume_group *_vg_read(struct cmd_context *cmd,
const char *vgname,
const char *vgid,
- unsigned precommitted)
+ unsigned precommitted,
+ int writing)
{
const struct format_type *fmt = cmd->fmt;
struct format_instance *fid = NULL;
@@ -4530,8 +4531,11 @@ static struct volume_group *_vg_read(struct cmd_context *cmd,
* we can also skip the rescan in that case.
*/
if (!cmd->can_use_one_scan || lvmcache_scan_mismatch(cmd, vgname, vgid)) {
- log_debug_metadata("Rescanning devices for %s", vgname);
- lvmcache_label_rescan_vg(cmd, vgname, vgid);
+ log_debug_metadata("Rescanning devices for %s %s", vgname, writing ? "rw" : "");
+ if (writing)
+ lvmcache_label_rescan_vg_rw(cmd, vgname, vgid);
+ else
+ lvmcache_label_rescan_vg(cmd, vgname, vgid);
} else {
log_debug_metadata("Skipped rescanning devices for %s", vgname);
}
@@ -4752,6 +4756,7 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
int missing_pv_flag = 0;
uint32_t failure = 0;
int writing = (read_flags & READ_FOR_UPDATE);
+ int activating = (read_flags & READ_FOR_ACTIVATE);
if (is_orphan_vg(vg_name)) {
log_very_verbose("Reading orphan VG %s", vg_name);
@@ -4766,13 +4771,23 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
return NULL;
}
- if (!lock_vol(cmd, vg_name, writing ? LCK_VG_WRITE : LCK_VG_READ, NULL)) {
+ /*
+ * When a command is reading the VG with the intention of eventually
+ * writing it, it passes the READ_FOR_UPDATE flag. This causes vg_read
+ * to acquire an exclusive VG lock, and causes vg_read to do some more
+ * checks, e.g. that the VG is writable and not exported. It also
+ * means that when the label scan is repeated on the VG's devices, the
+ * VG's PVs can be reopened read-write when rescanning in anticipation
+ * of needing to write to them.
+ */
+
+ if (!lock_vol(cmd, vg_name, (writing || activating) ? LCK_VG_WRITE : LCK_VG_READ, NULL)) {
log_error("Can't get lock for %s", vg_name);
failure |= FAILED_LOCKING;
goto_bad;
}
- if (!(vg = _vg_read(cmd, vg_name, vgid, 0))) {
+ if (!(vg = _vg_read(cmd, vg_name, vgid, 0, writing))) {
/* Some callers don't care if the VG doesn't exist and don't want an error message. */
if (!(read_flags & READ_OK_NOTFOUND))
log_error("Volume group \"%s\" not found", vg_name);
@@ -4883,29 +4898,36 @@ struct volume_group *vg_read(struct cmd_context *cmd, const char *vg_name, const
goto_bad;
}
- if (writing && !(read_flags & READ_ALLOW_EXPORTED) && vg_is_exported(vg)) {
- log_error("Volume group %s is exported", vg->name);
- failure |= FAILED_EXPORTED;
- goto_bad;
- }
+ /*
+ * If the command intends to write or activate the VG, there are
+ * additional restrictions. FIXME: These restrictions should
+ * probably be checked/applied after vg_read returns.
+ */
+ if (writing || activating) {
+ if (!(read_flags & READ_ALLOW_EXPORTED) && vg_is_exported(vg)) {
+ log_error("Volume group %s is exported", vg->name);
+ failure |= FAILED_EXPORTED;
+ goto_bad;
+ }
- if (writing && !(vg->status & LVM_WRITE)) {
- log_error("Volume group %s is read-only", vg->name);
- failure |= FAILED_READ_ONLY;
- goto_bad;
- }
+ if (!(vg->status & LVM_WRITE)) {
+ log_error("Volume group %s is read-only", vg->name);
+ failure |= FAILED_READ_ONLY;
+ goto_bad;
+ }
- if (!cmd->handles_missing_pvs && (missing_pv_dev || missing_pv_flag) && writing) {
- log_error("Cannot change VG %s while PVs are missing.", vg->name);
- log_error("See vgreduce --removemissing and vgextend --restoremissing.");
- failure |= FAILED_NOT_ENABLED;
- goto_bad;
- }
+ if (!cmd->handles_missing_pvs && (missing_pv_dev || missing_pv_flag)) {
+ log_error("Cannot change VG %s while PVs are missing.", vg->name);
+ log_error("See vgreduce --removemissing and vgextend --restoremissing.");
+ failure |= FAILED_NOT_ENABLED;
+ goto_bad;
+ }
- if (!cmd->handles_unknown_segments && vg_has_unknown_segments(vg) && writing) {
- log_error("Cannot change VG %s with unknown segments in it!", vg->name);
- failure |= FAILED_NOT_ENABLED; /* FIXME new failure code here? */
- goto_bad;
+ if (!cmd->handles_unknown_segments && vg_has_unknown_segments(vg)) {
+ log_error("Cannot change VG %s with unknown segments in it!", vg->name);
+ failure |= FAILED_NOT_ENABLED; /* FIXME new failure code here? */
+ goto_bad;
+ }
}
/*
diff --git a/tools/lvchange.c b/tools/lvchange.c
index 7bdf997..e7fb57d 100644
--- a/tools/lvchange.c
+++ b/tools/lvchange.c
@@ -1435,7 +1435,7 @@ int lvchange_activate_cmd(struct cmd_context *cmd, int argc, char **argv)
} else /* Component LVs might be active, support easy deactivation */
cmd->process_component_lvs = 1;
- ret = process_each_lv(cmd, argc, argv, NULL, NULL, READ_FOR_UPDATE,
+ ret = process_each_lv(cmd, argc, argv, NULL, NULL, READ_FOR_ACTIVATE,
NULL, &_lvchange_activate_check, &_lvchange_activate_single);
if (ret != ECMD_PROCESSED)
diff --git a/tools/pvscan.c b/tools/pvscan.c
index d41345f..12711cb 100644
--- a/tools/pvscan.c
+++ b/tools/pvscan.c
@@ -900,7 +900,7 @@ static int _pvscan_aa(struct cmd_context *cmd, struct pvscan_aa_params *pp,
return ECMD_PROCESSED;
}
- ret = process_each_vg(cmd, 0, NULL, NULL, vgnames, READ_FOR_UPDATE, 0, handle, _pvscan_aa_single);
+ ret = process_each_vg(cmd, 0, NULL, NULL, vgnames, READ_FOR_ACTIVATE, 0, handle, _pvscan_aa_single);
destroy_processing_handle(cmd, handle);
diff --git a/tools/vgchange.c b/tools/vgchange.c
index a17f456..aad6db3 100644
--- a/tools/vgchange.c
+++ b/tools/vgchange.c
@@ -800,8 +800,10 @@ int vgchange(struct cmd_context *cmd, int argc, char **argv)
cmd->lockd_vg_enforce_sh = 1;
}
- if (update || arg_is_set(cmd, activate_ARG))
+ if (update)
flags |= READ_FOR_UPDATE;
+ else if (arg_is_set(cmd, activate_ARG))
+ flags |= READ_FOR_ACTIVATE;
if (!(handle = init_processing_handle(cmd, NULL))) {
log_error("Failed to initialize processing handle.");
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